feat: L'Ami Fiduciaire V1.0.0 — full codebase with Story 0.1 complete

Initial commit of the L'Ami Fiduciaire SaaS platform built on Laravel 12,
Vue 3, Inertia.js 2, and Tailwind CSS 4.

Story 0.1 (rename folders to declarations in database) is implemented and
code-reviewed: migration, rollback, and 6 Pest tests all passing.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/Mail/FolderTextMessageMail.php

@@ -0,0 +1,55 @@
+<?php
+
+namespace App\Mail;
+
+use App\Models\Folder;
+use Illuminate\Bus\Queueable;
+use Illuminate\Mail\Mailable;
+use Illuminate\Mail\Mailables\Content;
+use Illuminate\Mail\Mailables\Envelope;
+use Illuminate\Queue\SerializesModels;
+
+class FolderTextMessageMail extends Mailable
+{
+    use Queueable, SerializesModels;
+
+    /**
+     * Create a new message instance.
+     *
+     * @param  string|null  $token  When set, recipient is client (use token-based URL). When null, recipient is comptable (use folders.show).
+     */
+    public function __construct(
+        public Folder $folder,
+        public string $body,
+        public ?string $token = null
+    ) {}
+
+    /**
+     * Get the message envelope.
+     */
+    public function envelope(): Envelope
+    {
+        return new Envelope(
+            subject: 'Nouveau message - '.$this->folder->title,
+        );
+    }
+
+    /**
+     * Get the message content definition.
+     */
+    public function content(): Content
+    {
+        $messagesUrl = $this->token
+            ? route('client.upload', ['token' => $this->token])
+            : route('folders.show', ['folder' => $this->folder]).'?tab=messages';
+
+        return new Content(
+            markdown: 'emails.folder-text-message',
+            with: [
+                'folderTitle' => $this->folder->title,
+                'body' => $this->body,
+                'messagesUrl' => $messagesUrl,
+            ]
+        );
+    }
+}